tree:   https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.13.y-rt-rebase
head:   7e175e6b59975c8901ad370f7818937f68de45c1
commit: 63cf1e4b564a46ec7bee5571cff518c70355dbdf [14/222] printk: add pr_flush()
config: powerpc64-randconfig-r003-20210708 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8d69635ed9ecf36fd0ca85906bfde17949671cbe)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install powerpc64 cross compiling tool for clang build
        # apt-get install binutils-powerpc64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/commit/?id=63cf1e4b564a46ec7bee5571cff518c70355dbdf
        git remote add linux-rt-devel https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
        git fetch --no-tags linux-rt-devel linux-5.13.y-rt-rebase
        git checkout 63cf1e4b564a46ec7bee5571cff518c70355dbdf
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from kernel/printk/printk.c:22:
   In file included from include/linux/kernel.h:12:
   In file included from include/linux/bitops.h:32:
   In file included from arch/powerpc/include/asm/bitops.h:62:
   arch/powerpc/include/asm/barrier.h:49:9: warning: '__lwsync' macro redefined [-Wmacro-redefined]
   #define __lwsync()      __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
           ^
   <built-in>:310:9: note: previous definition is here
   #define __lwsync __builtin_ppc_lwsync
           ^
   kernel/printk/printk.c:178:5: warning: no previous prototype for function 'devkmsg_sysctl_set_loglvl' [-Wmissing-prototypes]
   int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
       ^
   kernel/printk/printk.c:178:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
   ^
   static 
   kernel/printk/printk.c:2674:4: error: implicit declaration of function 'latched_seq_write' [-Werror,-Wimplicit-function-declaration]
                           latched_seq_write(&c->printk_seq, seq);
                           ^
   kernel/printk/printk.c:2907:2: error: implicit declaration of function 'latched_seq_write' [-Werror,-Wimplicit-function-declaration]
           latched_seq_write(&newcon->printk_seq, seq);
           ^
>> kernel/printk/printk.c:3633:17: error: implicit declaration of function 'read_console_seq' [-Werror,-Wimplicit-function-declaration]
                           printk_seq = read_console_seq(con);
                                        ^
   kernel/printk/printk.c:3633:17: note: did you mean '__up_console_sem'?
   kernel/printk/printk.c:238:13: note: '__up_console_sem' declared here
   static void __up_console_sem(unsigned long ip)
               ^
   2 warnings and 3 errors generated.


vim +/read_console_seq +3633 kernel/printk/printk.c

  3597	
  3598	/**
  3599	 * pr_flush() - Wait for printing threads to catch up.
  3600	 *
  3601	 * @timeout_ms:        The maximum time (in ms) to wait.
  3602	 * @reset_on_progress: Reset the timeout if forward progress is seen.
  3603	 *
  3604	 * A value of 0 for @timeout_ms means no waiting will occur. A value of -1
  3605	 * represents infinite waiting.
  3606	 *
  3607	 * If @reset_on_progress is true, the timeout will be reset whenever any
  3608	 * printer has been seen to make some forward progress.
  3609	 *
  3610	 * Context: Any context.
  3611	 * Return: true if all enabled printers are caught up.
  3612	 */
  3613	bool pr_flush(int timeout_ms, bool reset_on_progress)
  3614	{
  3615		int remaining = timeout_ms;
  3616		struct console *con;
  3617		u64 last_diff = 0;
  3618		bool may_sleep;
  3619		u64 printk_seq;
  3620		u64 diff;
  3621		u64 seq;
  3622	
  3623		may_sleep = (preemptible() && !in_softirq());
  3624	
  3625		seq = prb_next_seq(prb);
  3626	
  3627		for (;;) {
  3628			diff = 0;
  3629	
  3630			for_each_console(con) {
  3631				if (!(con->flags & CON_ENABLED))
  3632					continue;
> 3633				printk_seq = read_console_seq(con);

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org